02442nas a2200277 4500008004100000022001400041245010600055210006900161260010600230300001200336490000800348520141600356653003001772653001701802653001401819653001601833653002201849100002401871700003001895700001701925700002901942700002101971700002001992700002402012856012802036 2016 eng d a0277-538700aPhotoluminescent tetrahedral d(10)-metal Schiff base complexes exhibiting highly ordered mesomorphism0 aPhotoluminescent tetrahedral d10metal Schiff base complexes exhi aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcFEB a150-1580 v1053 a

A series of four-coordinate d(10)-metal complexes of the type [ML2] {M = Zn, Cd, Hg; L = 4-nitro-2-((octadecylimino)methyl)phenol}, incorporating a new N-alkylated bidentate [N,O]-donor salicylaldimine Schiff base ligand, has been synthesized and characterized by elemental analyses, FT-IR, UV-Vis, H-1 NMR and FAB-mass spectroscopies. The ligand is non-mesomorphic and devoid of any photoluminescence. The zinc(II) and cadmium(II) complexes displayed highly ordered mesophases reminiscent of soft crystals. The phases have been characterized by polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) studies. The complex of mercury(II) decomposed prior to melting. An orthogonal symmetry with a `herringbone' array for the zinc complex and a primitive triclinic symmetry (p(1)) for the cadmium complex, respectively, has been proposed. The complexes exhibited fluorescence at room temperature, both in the solution and in the solid state, with emission maxima in the blue region. Density functional theory (DFT) calculations carried out using the GAUSSIAN 09 program at the B3LYP level revealed a distorted tetrahedral geometry around the metal center in all the complexes. Natural bond orbital (NBO) analysis suggested appreciable charge transfer from the ligand to the metal center in the complexes. (C) 2015 Elsevier Ltd. All rights reserved.

10aDensity functional theory10aLuminescence10aMesophase10aSchiff base10aX-ray diffraction1 aChakraborty, Sutapa1 aPurkayastha, Debraj, Dhar1 aDas, Gobinda1 aBhattacharjee, Chira, R.1 aMondal, Paritosh1 aPrasad, Krishna1 aRao, D., S. Shankar uhttps://library.ncl.res.in/content/photoluminescent-tetrahedral-d10-metal-schiff-base-complexes-exhibiting-highly-ordered-102808nas a2200277 4500008004100000022001400041245012400055210006900179260000900248300001100257490000800268520186200276653002402138653001802162653001802180653001602198653002602214100002102240700002402261700002202285700002302307700001902330700003002349700002002379856013102399 2020 eng d a0167-732200aInfluence of gold nanorods on the structure and photonic bandgap in a twist grain boundary phase with smectic C* blocks0 aInfluence of gold nanorods on the structure and photonic bandgap cFEB  a1121170 v2993 a

We describe the first report of the influence of gold nanorods (GNR) on the induced twist grain boundary smectic C* (TGBC*) phase in a binary mixture of achiral bent-core and chiral linear liquid crystals. The GNR concentration-dependent phase diagram of these nanocomposites shows that the thermal range of this twist grain boundary phase having smectic C* blocks phase increases by 50% for an intermediate composition compared to that for the host binary mixture without nanorods. The inclusion of the nanorods is seen to have substantial effect on the structural and photonic bandgap features of the TGBC* phase. For example, the helical periodidty gets altered in all the three dimensions: while those within the block undergo a huge increase, the one which is orthogonal to the blocks, shrinks. The spacing of the square grid pattern arising normal to the TGB helix direction increases for the nanocomposites getting even doubled for a certain composition, a feature evidenced by optical microscopy as well as optical diffraction. Xray diffraction clearly brings out the feature that the presence of GNR alters the thermal character of the transition between the TGBC* and the cholesteric phase. Quantitative analysis of the data indicates that the system would remain in the vicinity of a possible tricritical point, a behavior having wider ramifications to understand the underlying critical phenomenon. Based on the experimental observations, and capturing the essence of the reported adaptive defect core targeting mechanism we propose a model wherein GNRs get confined in the grain boundary region. This feature offers a potential to have periodic and anisotropic plasmonic structure arising out of the synergetic interactions between the metal nanorod and the twisted grain boundary structure. (C) 2019 Elsevier B.V. All rights reserved.

10a3D photonic bandgap10aGold nanorods10aInduced phase10aTGBC* phase10aTricritical phenomena1 aSahoo, Rajalaxmi1 aRao, D., S. Shankar1 aHiremath, Uma, S.1 aYelamaggad, V., C.1 aShinde, Pravin1 aPrasad, Bhagavatula L. V.1 aPrasad, Krishna uhttps://library.ncl.res.in/content/influence-gold-nanorods-structure-and-photonic-bandgap-twist-grain-boundary-phase-smectic-c02813nas a2200241 4500008004100000022001400041245016300055210006900218260000900287300000800296490000700304520194400311653001602255653002202271653001102293653002002304653002502324100003002349700002102379700002402400700002302424856012402447 2020 eng d a0250-470700aWide thermal range, exclusive occurrence of technically significant chiral nematic phase: synthesis and mesomorphism of cholesterol-based non-symmetric dimers0 aWide thermal range exclusive occurrence of technically significa cAUG  a1880 v433 a

Fifteen new non-symmetric chiral dimers belonging to three different series have been synthesized and evaluated for their mesomorphic properties. They are formed by interlinking cholesterol with salicylaldimine (SAN) cores (with reverse imine groups) via an omega-oxyalkanoyloxy spacer. Within a series, the length of the terminaln-alkoxy tails has been varied for a fixed even-parity spacer. Three even-parity spacers such as 4-oxybutanoyloxy, 6-oxyhexanoyloxy and 8-oxyoctanoyloxy have been used to join two cores, whereas the terminal tails such asn-butyloxy,n-hexyloxy,n-octyloxy,n-decyloxy andn-dodecyloxy chains have been attached to the SAN core. Microscopic and calorimetric experimental results show that all the dimers behave identically exhibiting the chiral nematic (N*) phase solely, which was authenticated by powder X-ray diffraction studies carried out on some selected samples. In the vast majority of the cases, this phase is thermodynamically stable, and while cooling, it exists over a wide thermal range covering room temperature (RT) due to supercooling. This finding is notable given the fact that the N* phase possesses technologically significant optical properties. At RT, the N* phase displayed one of the iridescent colours characteristically caused by interference and diffraction of the reflected and scattered light. A comparative study reveals that the lengths of both the terminal chain and central spacer influence the clearing temperature of the dimers, and also the temperature range of the N* phase. The selective reflection measurements revealed that the pitch of the N* phase is either temperature sensitive or temperature insensitive. Temperature-dependent circular dichroism (CD) spectra were recorded for the planar texture of the N* phase formed by a dimer, as a representative case. The presence of an intense negative CD band suggests the left-handed screw sense of the N* phase helix.

10aCD activity10acholesteric phase10adimers10aliquid crystals10aselective reflection1 aNayak, Rashmi, Ashwathama1 aBhat, Sachin, A.1 aRao, D., S. Shankar1 aYelamaggad, V., C. uhttps://library.ncl.res.in/content/wide-thermal-range-exclusive-occurrence-technically-significant-chiral-nematic-phase